Mustard tolerance to clopyralid applied alone or with ethametsulfuron

• Published in: Canadian journal of plant science 1994-07, Vol.74 (3), p.635-641
• Main Authors: Loeppky, H.A, Blackshaw, R.E
• Format: Article
• Language: English
• Subjects: Agronomy. Soil science and plant productions; application rate; application timing; Biological and medical sciences; Brassica juncea; Chemical control; clopyralid; crop production; crop quality; crop yield; developmental stages; Fundamental and applied biological sciences. Psychology; metsulfuron; Parasitic plants. Weeds; Phytopathology. Animal pests. Plant and forest protection; phytotoxicity; tolerance; weed control; Weeds
• ISSN: 0008-4220; 1918-1833
• DOI: 10.4141/cjps94-114

Mustard is a drought-tolerant crop well adapted to the Brown and Dark Brown soils of the Prairies; however, lack of broad-leaved weed control limits production. Two field studies were conducted at Indian Head, Saskatchewan and Lethbridge, Alberta to determine the response of brown and oriental mustard (Brassica juncea (L.) Coss), and yellow mustard (B. hirta Moench) to clopyralid. Clopyralid was applied at 0.10, 0.15, 0.20, 0.30, 0.60 kg a.i. ha −1 at the 4- or 10-leaf stage in one experiment. The other was a factorial experiment of clopyralid at 0.10, 0.20, and 0.30 kg a.i. ha −1 with ethametsulfuron at 0.01, 0.02, and 0.03 kg a.i. ha −1 . Clopyralid applied at 0.15 kg a.i. ha −1 , the lowest rate at which it is registered for weed control in canola, resulted in brown mustard yield reductions of 21%, oriental mustard yield reductions of 23% and yellow mustard yield reductions of 9% over 5 site years. This rate of clopyralid applied with ethametsulfuron reduced brown, oriental and yellow mustard yield by 30, 33 and 8%, respectively. Oil content was also reduced by clopyralid. Clopyralid cannot be used for weed control in mustards. Key words: Crop tolerance, growth stage, clopyralid, ethametsulfuron, seed yield, oil content